This invention relates to the production of isoprene and specifically to a process for the production of isoprene from isobutylene and formaldehyde.
Isoprene is chiefly used as a starting material in the production of synthetic rubbers. As the demand for high quality grades and high volumes of rubber products is increasing, isoprene is becoming a very significant commercial commodity and a cheap and efficient way of producing isoprene would be of great value in the chemical industry.
Many processes for the synthesis of isoprene have been proposed but in many ways the most attractive is that in which isobutylene and formaldehyde are reacted in the presence of a catalyst. Such processes are exemplified by the disclosures in U.S. Pat. Nos. 3,662,016; 3,146,278; 3,437,711 and 3,621,072. Catalyst proposed in the prior art include alumina, silica/alumina, phosphoric acid in conjunction with chromium oxide or manganese dioxide, a mixture of silica and antimony oxide, and phosphoric acid treated with a group II metal oxide or hydroxide.
However, it is found that the prior art catalysts often produce undesirably large quantities of by-products such as polymerized isobutylene. There is, therefore, a need for a catalyst having improved selectivity towards the desired product.
A modified catalyst has now been discovered that has such increased selectivity to isoprene while retaining a high conversion rate.
Thus the present invention has as its primary object the provision of a process for the production of a novel catalyst suitable for use in the reaction of isobutylene with formaldehyde to produce isoprene.
A further object of the present invention is to provide a process for the production of isoprene using such novel catalyst.